timer delay question please help!

[EEs_Rule]

Hello everyone,

First I would like to thank everyone for their input on all the other threads. As a newbee I have learned a lot from everyone and checked out most of the tutorials that I saw mentioned in the threads. I am still a little confused on the subject of timers and delays.

I am working on a project which requires two delays, a 20 sec delay, and a 40µsec delay. I am using the PIC12F683. I am not sure what prescale value to use, and which internal clk frequency i should use it with (which is best for a 20 second delay?). Aslo, how do I calculate the value to count down from? I know I cannot just say count down from 20. Any help on this topic will be greatly appreciated.

 

[be80be]

Try this site out Delay Loops - Delay Loop - PIC Microcontroller Tutorials - PIC Tutorial Resource - Connect to the PIC

 

[Gayan Soyza]

Since you are using PIC12F683 I'd prefer go with TMR2.

You need three variables,

To generate 20S

PS=1:1,PR2=249

Count1	= 40 
Count2	= 100
Count3	= 20

250 X 40 X 100 X 20 = 20Sec

To generate 40uS

PS=1:1,PR2=39
40 X 1 X 1 X 1 = 40uS